Dynamometer-loaded turboexpander

When power levels are low or cannot otherwise be utilized, a dynamometer or an air brake (blower) may be used. Figure 3-11 shows a typical dynamometer-loaded turboexpander cross-section. 

The choice of a turboexpander load may be influenced by the desire to optimize refrigeration. In other words, a dynamometer load may be chosen over a generator load due to speed considerations. Additionally, there are other constraints imposed on optimal design. Factors such as impeller peripheral velocity (tip speed), bearing design, axial load balance, material selection, and manufacturing methods (which have greatly improved in the recent decades) all have an influence. 

Most ethylene plants operate continuously with the expanders operating at or near design conditions. If necessary, due to their unique design characteristics, radial inflow turboexpanders can accommodate a wide range of process conditions without significant losses in thermal or mechanical efficiency. Expanders may be loaded with booster compressors, gear-coupled generators, dynamometers, or other in-plant mechanical equipment such as pumps. In ethylene plants, turboexpanders are typically used in eitlier post-boost or pre-boost applications. 

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See also in sourсe #XX -- [ ]

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